The miniaturization of data processing equipment for portability and ease of use is becoming increasingly important. The limiting factor for reducing the size of portable data processing equipment is generally the keyboard which requires sufficient space for the keys and for the extensive mechanics to convert keystrokes to electrical connections which indicate operation of the keys. The keys are limited in their horizontal size and spacing by the size of an average operator's fingers and hands.
Thus, it is desirable to reduce the vertical dimension, or "thickness", of the keyboard as much as possible. A typical portable data processor, or "portable personal computer" or "personal digital assistant", has a keyboard panel and a display panel, and the data processor is incorporated within one of the panels. The two panels are then folded together so that the bottom of the keyboard panel and the back of the display panel form an outer case for the folded unit. By reducing the thickness of the keyboard, the thickness of the overall folded unit may also be reduced, making the folded portable data processing unit easier to handle and to carry.
Prior U.S. Pat. No. 5,457,453, Chiu et al., unassigned, illustrates a keyboard having reduced thickness when folded, by moving otherwise conventional plunger keys to depressed positions when folding is to occur.
Prior U.S. Pat. No. 5,280,147, Mochizuki et al., assigned to Brother Kogyo Kabushiki Kaisha, reduces the thickness of the keyboard by the use of scissors-like pivotally connected support levers with pivot connections at one end of each lever to respectively the base and the key, and sliding pivot connections at the opposite ends. A conventional nonlinear rubber spring or "dome" is used to transmit the keystroke to electrical contacts to make the connection, indicating operation of the key.
It is desirable to reduce the height of the keyboard even further as well as to reduce the number of parts and to provide an easily assembled keyboard.